The present invention relates to rolling-type bearings, and more particularly, to separators for rolling-type bearings.
Bearings, such as rolling-type bearings, are used to support the wheels of vehicles, among other uses. Rolling-type bearings, such as ball bearings, are popular because rolling resistance is demonstrably much less than sliding resistance. These bearings, then, are characterized by rolling elements, such as balls or rollers, confined between outer and inner rings, referred to as races. The rolling elements are usually spaced uniformly by a cage, referred to as a separator. The rolling elements are important because they transmit loads from moving parts of a machine to stationary supports.
When balls are used as rolling elements, they may be uniformly spherical. When rollers are used, they may be straight cylinders, or they may be barrel- or cone-shaped, or of other forms, depending upon the purpose of the bearing design. The races supply smooth, hard, accurate surfaces for the balls or rollers to roll on. In certain bearings, there may only be the inner or outer race, and the rollers or balls operate directly upon a suitably hardened shaft or housing. Further, rolling surfaces may be machined in the inner and outer races in order to provide close tolerances of size, surface finish, and roundness between the surfaces and the rolling elements of the bearings. This will provide a smooth rolling surface for the rolling elements. The rolling elements then rotate as a shaft rotates in order to minimize friction and wear on various components of the machine. In many embodiments, lubricants may be introduced to the bearing, and particularly to the rolling elements, to further reduce friction and wear, and in order to prolong the life of the bearing.
The bearing generally includes a bore disposed through the inner race. This bore is adapted such that a shaft may be disposed through the bore and journalled to the bearing. Rotational motion of the shaft may be used to maintain a load-supporting lubricant film between the inner and outer races, which provide annular support surfaces on the inner surfaces of the bearings and the outer surface of the shaft. Rotation of the shaft will draw lubricant into one or more small clearance spaces between the shaft and the load bearing surfaces of the bearings.
Various generations of bearing-style drive and nondrive wheel bearing assemblies that feature separators, for load carrying capabilities and minimum torque/drag performance, are typically faced with difficult methods of properly lubricating and/or greasing the rolling elements of the bearing assembly. This difficulty generally arises because the lubrication of the bearing assembly occurs from outside the bearing assembly after the bearing has been assembled.
In a typical assembly, the rolling elements of the bearing are located in the interior of the bearing housing and a certain distance inward from each end of the bearing housing. Thus, in order to properly lubricate the rolling elements, lubricant must be forced into the separator of the bearing from either one end of the bearing, or by introducing lubricant from each end of the preassembled bearing. Additionally, other bearing components, such as speed sensor rings and/or inner ring components, can provide further physical obstacles which prevent proper positioning of the lubricant in the separator of the bearing. Further, difficulty in lubrication may arise because many bearings may include more than one separator.
Currently, the typical solution to this lubrication problem is to provide a sufficient quantity of lubricant in the bearing assembly in order to ensure that the ball rows will receive some lubrication. This technique is generally referred to as xe2x80x9cvolume greasingxe2x80x9d. In this method, first, the free or open space (in volume) between the internal components of the bearing is calculated. Second, a predetermined volume of a lubricant, such as grease, is forced into the bearing in an axial direction. By this method, some of the lubricant will reach the separator of the bearing. However, as described above, much of this lubricant may be blocked from reaching the separator by other components of the bearing.
A second problem with this method of lubrication is that the lubricant may not be evenly distributed radially, in addition to the axial lubrication problem noted above. This can translate into the pushing of a concentrated section of grease, or other lubricant, away from the rolling elements as the rolling elements begin to turn, thus leading to the problems of friction and wear.
A third problem with this lubrication method is higher costs. This method of volume greasing requires an excess of the proper amount of grease required to lubricate the bearing for its normal design life, due to the open volume of a particular bearing design. This excess use of lubricant leads to higher costs of manufacture.
Yet a fourth problem is that the oil bleed, or separation, from this higher volume of grease can build up and be forced out of the bearing assembly through the sealing systems and onto corner brake components. This reduces the amount of lubricant in the bearing and can lead to increased problems with friction and wear.
Thus, in view of the above drawbacks with current methods of lubricating balls and bearings, it would be desirable to provide a separator and bearing assembly which requires less lubricant for proper bearing lubrication, and reduces the cost of bearing manufacture, while providing evenly distributed lubrication to each rolling element of a bearing assembly.
The present invention reduces and eliminates the drawbacks with current methods of lubricating rolling elements of bearings. The present invention does so by providing a separator for a bearing, which includes a frame for housing the rolling elements, such as balls, of the bearing. This frame includes a plurality of cavities for receiving the rolling elements and further includes a lubrication channel. This lubrication channel is in fluid communication with each of the cavities of the separator. Grease and/or another lubricant may be provided within the channel prior to assembling the separator in the bearing assembly. The lubricant flows through the channel and into each of the cavities in order to lubricate the rolling elements so that they may roll on the surfaces of the races of the bearing with minimal friction and wear. Following insertion of the rolling elements into the cavities of the separator, the lubrication channel is filled with a lubricant, such as grease, and the separator is introduced into a bearing including an outer race and an inner race. Once inserted into the housing of the bearing, the separator is disposed within the outer race and inner race with the plurality of rolling elements disposed between the outer race and inner race and in movable contact with the races.
The lubrication channel design permits the assembly of the rolling elements into the separator, as normal, outside of the bearing assembly. However, the separator subassembly can be transferred to a lubrication station outside of the bearing assembly for introduction of a lubricant into the channel prior to final assembly of the separator into the bearing. At the same time, prior to final assembly, one can simultaneously check for ball presence, evacuate air from the open cavity, and then fill the open cavity with grease or other lubricant. Each xe2x80x9cpre-greasedxe2x80x9d bearing separator subassembly can then be installed into the bearing assembly. This design permits a maximum volume of evenly distributed grease to each rolling element while eliminating the need for volume greasing.
The present invention ensures continued and directed lubrication for the rolling elements of the bearing assembly, thus assuring proper lubrication for the design life of the bearing assembly. Additionally, the lower volume and placement of lubricant in the bearing assembly will reduce bearing manufacturing costs and reduce the probability of lubricant bleed problems as noted above in the Background of the Invention. The lubrication channel design also reduces axial space outside of the rolling elements in the bearing design. The present invention also provides the advantages of allowing for a pre-greased separator subassembly, which can then be provided by component suppliers.